Check for malware on outgoing mail

How could I prohibt relaying of outgoing mails which contain malware? The standard behaviour of ispconfig mail configuration seems to be not checking this.

In which file have I to change what settings? I would like 1.) to send an email back to my mail sending customer with a warning about the interrupted mail transfer and deleted mail - and of course: delete the mail - and 2.) to deny incoming malware mails after virus checking and sending back a deny message to the sending server logs, which seems also not to be the standard configuration of ispconfig.